Blackfin arch: show_mem can not be marked as init, since it is called during OOM condition

show_mem can not be marked as init, since it is called during
OOM condition from /mm/oom_kill.c:out_of_memory() and
/mm/page_alloc.c:__alloc_pages()

Signed-off-by: Robin Getz <robin.getz@analog.com>
Signed-off-by: Bryan Wu <bryan.wu@analog.com>